Active mineral additive to binding materials

ABSTRACT

Active mineral additive to binding materials, consisting of granulated phosphatic slag 94-98% by mass and sulphate containing component 2-6% by mass, which is a mixture of sodium sulphate 47.2-57.6% by mass, magnesium sulphate 40.5-51.1% by mass and sodium rhodonite 1.7-1.9% by mass.

FIELD OF THE INVENTION

The present invention relates to the production of binding materials andmore particularly it relates to an active mineral additive for bindingmaterials.

BACKGROUND ART

Known in the art is the production of cements that includes, apart fromPortland cement clinker and gypsum, the additional use of active mineraladditives, the weight fraction of which accounts for 5 to 60% by mass.Introduction of active mineral additives into cement makes it possibleto cut down its cost and in some cases to modify the construction andengineering properties of cement (for instance cement hardeningkinetics, heat release, setting periods, resistance to sulphates).

Both artificial and natural mineral additives can be used as activemineral additives in cement production. Natural mineral additivesinclude: diatomite, tripolite, opoka, melilite marble aggregate.Artificial mineral additives include blast furnace and phosphatic slags.

Natural mineral additives have low whiteness and hydraulic activity,which the whiteness of Portland cement and its construction andengineering properties.

Known in the art is an active mineral additive, which is a heat treatedmixture (at 1350°-1450° C.) of phosphatic slag (92-99% by mass) andsodium sulphate (1-8% by mass) (SU, A, 893925). The whitenesscoefficient of such mineral active additives, according to the absolutescale, is considerably higher than that of natural mineral additives andamounts to 89-93% and the hydraulic activity of this additive determinedby the amount of lime absorbed by the additive in 15 titrations is22.9-23.8 mg.

Known in the art is also an active mineral additive, that is subjectedto melting at 1350°-1450° C. mixture of phosphatic slag, sodium sulphateand magnesium sulphate.

The use of such mineral additive fails to considerably enhance thewhiteness, and hydraulic activity of cement.

SUMMARY OF THE INVENTION

The present invention solves the problem of providing an active mineraladditive, which ensures higher whiteness and hydraulic activity of thecement produced on the basis of this additive.

This object is attained by providing an active mineral additive tobinding materials, comprising granulated phosphatic slag and asulphate-containing component, according to the present invention,comprises as said sulphate containing component compries a mixture ofsodium sulphate, 47.2-57.6% by mass, magnesium sulphate, 40.5-51.1% bymass, and sodium rhodonite 1.70-1.90% by mass. The following ratio ofcomponents are present in the mineral additive:

phosphatic slag--94-98% by mass

sulphate-containing mixture --2-6% by mass.

According to the present invention, the whiteness coefficient of theactive mineral additive determined by the absolute scale is 96-100% andits hydraulic activity determined by the absorption of Ca(OH)₂ from limesolution after 15 titrations is 24.14-24.97 mg.

Further objects and advantages of the present invention will beunderstood from the following detailed description of the active mineraladditive and examples of its production and use.

DETAILED DESCRIPTION

The active mineral additive for cement, according to the presentinvention, is a mixture of granulated phosphatic slag in an amount of94-98% by mass and a sulphate-containing mixture in an amount of 2-6% bymass. The sulphate containing mixture comprises sodium sulphate(47.2-57.6% by mass), magnesium sulphate (40.5-51.1% by mass) and sodiumrhodonite (1.7-1.9% by mass).

Phosphatic slag, which is the basic component of the mineral additivecontained in the amount of 92-96% by mass, appears to be a product ofelectrothermal production of yellow phosphor.

In chemical composition phosphatic slag usually consists of 38-45% bymass of silicon oxide, 2-5% by mass aluminium oxide, 0.1-0.5% by mass ofiron oxide, 38-52% by mass of calcium oxide, 2-5% by mass of magnesiumoxide, 0.5-3.0% by mass of phosphorus oxide, 1-3% by mass of fluorine,0.1-0.3% by mass of manganese oxide, 3.0-5.0% by mass of calcium, ironand manganese phosphides.

In mineralogical composition granulated slag consists of 80-95% by massof vitreous phase of wolastonite composition and 7-10% by mass ofwollastonite, 5-7% by mass of mililite, 3-5% by mass of okermanite. Incrstallied state phosphatic slag consists of 60-70% by mass ofwollastinite, 20-30% by mass of mililite, 10-15% by mass of okermaniteand 10-20% by mass of cuspedine.

The sulphate-containing component of the active mineral additive,according to the present invention, consists of 47.2-57.6% by mass ofsodium sulphate, 40.5-51.1% by mass of magnesium sulphate and 1.7-1.9%by mass of sodium rhodonite.

The sulphate-containing component in the indicated composition suitable,according to the present invention, for the active mineral additive canbe produced both by blending the indicated components and throughneutralization of effluents from nitron production.

The active mineral additive to binding materials, which is claimed inthe present invention, may be produced either by introducing theindicated sulphate-containing component into melted phosphatic slag,subsequent mixing of the obtained composition and its introduction intowater, or by mixing the indicated components of the additive, melting ofthe obtained composition at 1400°-1700° C. and subsequent pouring of theproduced melt into water.

The sodium and magnesium sulphates contained in the sulphate-containingcomponent react with iron and manganese sulphides and phosphides,present in phosphatic slag, to form slightly colored or colorlesscompounds, thereby enhancing the whiteness of the slag.

With decreased content of magnesium and sodium sulphates in thesulphate-containing component below the indicated level no completechemical reaction with the above sulphides and phosphides of phosphaticslag occurs, thereby failing to result in the desired effect.

An increase in the content of magnesium and sodium sulphates in thesulphate-containing component above the indicated level is inexpedient,since this provides no rise of the whiteness coefficient.

Sodium rhodonite present in the sulphate-containing component, reactingwith metal sulphides of phosphatic slag, forms readily volatile slightlycolored components-iron and manganese rhodonites. The slag becomeswhiter not only due to the formation of slightly colored iron andmanganese rhodonites, but also due to the ability of sodium rhodonite tocatalize the reaction of slag sulphides with sodium and manganesesulphates at a temperature of 1400°-1700° C.

The increase in the hydraulic activity of the active mineral additiveaccording to the invention is explained by the fact that sodiumrhodonite anion causes a dispersion of silicon-oxygen complexes--Si--O--Si in phosphatic slag, thereby leading to its acceleratedhydration.

Experimentally it was found that the use of sulphate-containing mixturein the amount above 6% by mass is inexpedient, since no further increasein the whiteness of the additive occurs, but at the same time thesulphate-containing mixture affects the color stability of the additiveto be obtained.

When sulphate-containing mixture is used in the amount below 2% by mass,no sufficient oxidation of metal sulphides occurs. Apart from this, theuse of sulphate-containing component in the amount below 2% by mass,leads to the formation of a small amount of readily volatile andslightly colored compounds-metal rhodonites, thereby resulting in adecrease in the whiteness of the mineral additive.

According to the present invention, the whiteness coefficient of theactive mineral additive determined by the absolute scale amounts to96-100% and its hydraulic activity determined by the absorption ofCa(OH)₂ from lime solution after 15 titrations is 24.14-24.97 mg.

The active mineral additive according to the invention makes it possibleto enhance the quality of white and decorative binding materials and cutdown the cost of their production.

EXAMPLES

For a better understanding of the present invention specific examples ofits embodiments are given hereinbelow by way of illustration.

EXAMPLE 1

Granulated phosphatic slag in the amount of 98 kg and asulphate-containing component, which is a mixture consisting of sodiumsulphate 47.2% by mass magnesium sulphate 51.1% by mass, sodiumrhodonite 1.7% by mass, in the amount of 2 kg are blended and subjectedto melting at 1400°-1470° C.

The obtained melt is allowed to stand for 30 minutes and thereafter ispoured off into water.

The active mineral additive obtained as a result thereof had thewhiteness coefficient of 96%. The hydraulic activity of the obtainedadditive determined by the absorption of Ca(OH)₂ from lime solutionafter 15 titrations is 24.6 mg.

On the basis of the active mineral additive obtained (10% by mass),white Portland cement clinker (85% by mass) with addition of gypsum (5%by mass) binding materials is produced having a compressive strength of975 kgf/cm² (after 7 days of hardening) by joint grinding of the abovecomponents.

EXAMPLE 2

Under conditions similar to those described in Example 1, active mineraladditive is produced from granulated phosphatic slag in the amount of96.78 kg and sulphate-containing component, which is a mixture of sodiumsulphate 57.6% by mass, magnesium sulphate 40.5% by mass and sodiumrhodonite 1.9% by mass in the amount of 3.22 kg. The whitenesscoefficient of the additive obtained is 96%. The hydraulic activity ofthe produced additive determined by the absorption of Ca(OH)₂ from limesolution after 15 titrations is 24.7 mg.

On the basis of the obtained active mineral additive (20% by mass),white Portland cement clinker (75% by mass) with addition of gypsum (5%by mass) binding materials are produced having a compression strength of95 kgf/cm² (after 7 days of hardening) by joint grinding of theindicated components.

EXAMPLE 3

Under conditions similar to those described in Example 1, active mineraladditive is produced from granulated phosphatic slag in the amount of95.43 kg and sulphate-containing component, which is a mixtureconsisting of sodium sulphate 51.3% by mass, magnesium sulphate 46.9% bymass and sodium rhodonite 1.8% by mass, in the amount of 4.57 kg. Thewhiteness coefficient of the obtained additive is 99%, and its hydraulicactivity is 24.97 mg.

On the basis of the obtained active mineral additive (30 wt. %), whitePortland cement clinker (65 wt. %) with addition of gypsum (5 wt. %)binding material is produced having a compressive strength of 830kgf/cm² (after 7 days of hardening) by joint grinding of the indicatedcomponents.

EXAMPLE 4

Sulphate-containing component in the amount of 5.31 kg, which is amixture similar to the one described in Example 1, is added to a melt ofphosphatic slag in the amount of 94.69 kg at a temperature of1400°-1470° C.

The melt is homogenized and allowed to stand for 5-10 minutes.Thereafter the melt is poured into water.

The whiteness of the obtained active mineral additive amounts to 99%,its hydraulic activity determined by the absorption of Ca(OH)₂ from limesolution after 15 titrations is 24.9 mg.

On the basis of the obtained active mineral additive (40% by mass),white Portland cement clinker (55% by mass) with addition of gypsum (5%by mass) a binding material is produced having a compression strength of713 kgf/cm² (after 7 days of hardening) by joint grinding of theindicated components.

EXAMPLE 5

Under conditions similar to those described in Example 1, active mineraladditive is produced from granulated phosphatic slag in the amount of 94kg and sulphate-containing component, having a composition similar tothe one described in example 2, in the amount of 6 kg.

The whiteness coefficient of the obtained additive amounts to 100%. Itshydraulic activity determined b the absorption of Ca(OH)₂ from limesolution after 15 titrations is 24.14 mg.

The compression strength of the binding material produced in conditionssimilar to those indicated in Example 3 amounts to 830 kgf/cm² (after 7days of hardening).

INDUSTRIAL APPLICABILITY

The present invention will find application in the production of cement,in particular: white and colored Portland cement, used for finishingbuildings and various structures, Portland cement with mineraladditives, Portland blast furnace cement and slag binding materials withimproved properties.

Apart from this, the invention will find application in the manufactureof ceramic products and glass-crystalline materials with specialproperties.

We claim:
 1. An active mineral additive for use in binding materials,said additive comprising granulated phosphatic slag in an amount ofabout 94-98% by mass and a sulphate-containing mixture in an amount ofabout 2-6% by mass, said sulphate-containing mixture consistingessentially of the following components in percent by mass:

    ______________________________________                                        sodium sulphate  47.2-57.6                                                    magnesium sulphate                                                                             40.5-51.1                                                    sodium rhodonite 1.70-1.90                                                    ______________________________________                                    


2. An improved additive of the type comprising phosphatic slag, sodiumsulphate and magnesium sulphate for use in a binding material, theimprovement comprising an amount of sodium rhodonite effective toenhance the whiteness and hydraulic activity of said additive.
 3. Anadditive as claimed in claim 2 wherein said additive has a whitenesscoefficient of 96-100% on the absolute scale.
 4. An additive as claimedin claim 3 wherein the additive has a hydraulic activity, determined bythe absorption of Ca(OH)₂ from lime solution after 15 titrations, of24.14-24.97 mg.
 5. In a method for producing a binding material bycombining an additive comprising phosphatic slag and a sulphatecontaining component with Portland cement and gypsum, the improvementcomprising including in said sulphate containing component an amount ofsodium rhodonite effective to enhance the whiteness and hydraulicactivity of said binding material.
 6. A method as claimed in claim 5wherein said phosphatic slag is present in said additive in an amount ofabout 94-98% by mass and said sulphate containing component is presentin said additive in an amount of about 2-6% by mass.
 7. A method asclaimed in claim 6 wherein the sulphate containing component consistsessentially of sodium sulphate in an amount of 47.2-57.6% by mass,magnesium sulphate in an amount of 40.5-51.1% by mass and sodiumrhodonite in an amount of 1.70-1.90 percent by mass.